A. Field of the Invention
This particular invention is directed to a method of forming a locking collar of the type adapted for locking the inner ring of an antifriction bearing assembly to a shaft. More specifically, it is related to a method of deforming the periphery of the side wall forming a formed counterbore radially inwardly to thereby form an internal conical locking surface.
B. Description of the Prior Art
In most antifriction bearing applications, the bearing assembly is mounted in a stationary housing by a press fit. A shaft is inserted into the bore of the bearing for rotational support with minimal friction. Due to axial and radial loads on the shaft, however, the relative axial and radial position of shaft and bearing will change. For most modern applications, this is an undesirable situation since the relative position of shaft and bearing assembly must be maintained within very close limits both radially and axially. Therefore, it has become common to lock the inner ring of the bearing and the rotation shaft together. In many cases, a press fit locks the ring and bearing together. In many installations, however, a press fit is not practical when, for instance, a long shaft is supported in the middle by a bearing. A press fit by the very nature of the forces required is almost impossible to accomplish over a span of more than a few inches. As a result, many shafts are mounted in bearings with a slip fit or even a loose fit. In such cases, locking the two members together is generally accomplished by either a set screw, a locking nut, or a locking collar, and it is generally accepted in the art that the most satisfactory locking mechanism for long shaft applications is the locking collar.
The mating conical surfaces of the locking collar and the inner ring are important because it is this feature that keeps the two parts from axially separating when the parts are in the locking position on a shaft. As can be appreciated, tolerances between the interfitting components are critical. The usual practice has been to machine the external eccentric cone on the extension of the inner bearing ring and the mating eccentric internal conical surface was then machined as an eccentric of the counterbore of the locking collar.
Previously forgings, bars, or tube stock were used as the raw material from which to make the locking collar. The actual forming, however, was done by machining with considerable loss of stock as scrap where metal was removed. Machining was chosen as the practical method to produce the part because of the difficulty of making a reverse cone or conical surface on the inside of the eccentric counterbore by any other method.
The forming of a normal internal cone in which the outboard diameter is larger than the inboard diameter is taught in the prior art, as described in U.S. Pat. No. 3,531,970 which was assigned to the assignee of the present application. U.S. Pat. No. 3,531,970 teaches a method of forging external races, known as cups, for tapered roller bearings. The same general technique may be followed for producing the ring with a counterbore in the present invention. However, the particular method described by the foregoing patent does not teach a final forming operation which is as simple, reliable and inexpensive as that of the present invention.
U.S. Pat. Nos. 2,728,616 and 3,239,292 disclose typical locking collar constructions. That of Potter, U.S. Pat. No. 2,728,616, is perhaps the most popular general design in use in the industry. In both patents, however, the basic conical surfaces are machined as aforesaid with considerable cost in time, labor, and material.